Cast Resin Parts

Discussion in 'Scratchin' & Bashin'' started by Bill Stone, Oct 24, 2002.

  1. philip

    philip Guest

    #81544 micro mark casting resin(CR300)

    Bill: Will this stuff really get into the nooks and crannies with intricate patterns such as old building brackets? O-scale?

  2. Bill Stone

    Bill Stone Member

    Hi Philip,

    In a word --- yes. You can't see it well in the photos in my first post of this thread, but there are a "handle" and two "brackets" on the (HO) door. They were made of round wire flat against the door, and came out perfectly round in the cast parts. In fact I carelessly left a minute gap between the wire and the door on one (had to cut the RTV in that little spot to get the mold off the pattern) and the molded parts reproduce that gap perfectly.

    I was really knocked out at how easy it is using this technique to produce perfect multiple parts. I've seen parts molded by others using the same stuff, parts far more exotic than the one I did here, and they all looked perfect.

    One good precaution is to follow directions and pour the casting resin into one corner of the mold --- this allows the stuff to push air bubbles ahead of it and out, rather than trap them.

    But even if a person only got a good part out of every other pour, the stuff goes a long way, and you can just toss the parts that didn't come out right. The Micro-Mark RTV and resin sounds expensive, but you'd have to create hundreds of small parts to use it all up, so the per-part cost is pennies.

    Bill S
  3. philip

    philip Guest

    Bill, need more advise.

    Bill: I have poured a whole lots of hydrocal and this resin stuff is a whole new ball game. The picture shows one of my miserable attempts with a two- part auto epoxy just to practice with. I have a friend that models O-scale and he has kind of talked me into doing 50 of the shown brackets and 12 of some even smaller ones for some sort of architectural overhang. The two- part epoxy I'm practicing with is like Karo Syrup so gooey it could never flow into the minute crevices. Can this Micro-Mark two- part resin be measured using two syringes.. to conserve the product. I only have two cavity molds. At 10 minutes per demold I''ll be real old before the process is finished.


    Attached Files:

  4. Bill Stone

    Bill Stone Member

    The Micro-Mark resin is fairly thin --- probably not much more viscous than water. I see no reason why you couldn't use syringes to measure it. (And measuring is a snap as it is 1:1.) In the molding I've done so far, I mix in the little paper "bathroom" cups, and have always just made rough guesses on proportions. As I've not had a bad batch yet, I'd guess that the mix isn't too super critical. By the way, the resin bottles are plastic, with dispenser caps, so are easy to use.

    If you have the original pattern, why not make six or eight RTV molds. You'd get more parts per pour, and wouldn't be too aged when you're finished.

    By the way, the resin is clear when it's liquid (which is nice for looking down into it to see if it covered everything, and cures to an opaque white (nice for inspecting the parts.)

    On a fairly complex part like your brackets, you might want to vibrate the mold after it's poured or snap it a few times with your finger to shake any bubbles loose so they'll rise to the top.

    Bill S
  5. philip

    philip Guest

    Bill: Thanks for the info. I'll most likely make multiple mold to speed the process.

  6. philip

    philip Guest

    alumilite casting

    My LHS only carries Alumilite casting material. Anyhow I bought 32oz's and it works great. Thanks Bill:D

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